Sami doesn't know what we the audience knows....and even based on what we know it still looks like the evidence is mounting against Ej. At the very, very least Sami should be cautious and not just telling everyone that Ej didn't do it, that he couldn't have possibly done it, that he would never do that....because as we all know...he's done it before, he's certainly capable of doing it again and he would certainly do it again if need be. So in the end, yes, Sami does look stupid NOW, by saying those things even if she technically is right and the others are wrong.....

Sami has made the decision to trust EJ, and she made that choice because of his actual actions. Even if she's not 100% certain, she should at least be loyal enough to defend him to outsiders, not immediately throw him under the bus and hand Hope more ammunition against EJ, by letting her think that even Sami thinks he might have done it.